Remove all the first Zero from the String

 There is a Pattern that needs  to follow:

X?	X, once or not at all
X*	X, zero or more times
X+	X, one or more times
X{n}	X, exactly n times
X{n,}	X, at least n times
X{n,m}	X, at least n but not more than m times

Code:

string s ='0004400';

string s1= s.replaceFirst('^0{2}','');

system.debug('string is '+s1);

Example

 s.replaceFirst('^0{2}',''); output: 0400

 s.replaceFirst('^0+',''); output: 400

 s.replaceFirst('^0?',''); output: 00400